Polyurethane elastomers are well-known for use in applications where durability is an essential characteristic. For example, these elastomers are well-known for use in molded products and as the material for shoe soles. These polyurethane elastomers are also advantageous for use as backing materials in commercial carpet tiles, as these elastomers provide the necessary durability for heavy traffic use over an extended period of time; for example, see Terry U.S. Pat. No. 3,705,834. Accordingly, much research and development have been dedicated to the manufacture of polyurethane elastomers in order to insure such durability on a consistent basis.
Many processes are known for the manufacture of polyurethane elastomers, an example of which involves the reaction of an isocyanate and a polyol in the presence of water and a catalyst. Various metal salts, such as bismuth salts, are known catalysts for these reactions. In some instances, the initiation of catalytic activity must be delayed and the polymerization reaction rate must be adjusted in order to obtain the desired processing and complete curing of the elastomer. Once initiated, however, the polymerization reaction should be rapid and sustainable in order to complete the manufacture of the polyurethane elastomers.
These parameters and requirements for the polymerization reaction are difficult to achieve with the current processes and, therefore, such processes may result in premature initiation of the catalytic activity and/or incomplete curing of the elastomer.
Therefore, a need exists for a process for the manufacture of polyurethane elastomers in which the rate of reaction can be adjusted in order to obtain the desired results.